Comment 66 for bug 151162

Another option that may not be cleaner but clearer. In this front end, write to a temp file and transfer it as a 'move' with x-moz-file. Then we may be able to drag attachments to text editors or pdf readers etc.
If x-moz-file transfers aren't working then those are something that probably should be fixed in 1.9.1 whereas the moz-file-promise ones need looking into.
I'm not sure what the need for the x-moz-file-promise-xxx flavors originated that separates them from a simple temp file transfer, but maybe for TB3 we should avoid them altogether until they are revamped for use the same way in all platforms.